Botulism is caused by Clostridium botulinum. The bacteria live in the upper layers of the soil. From here they spread to dead animals, standing pools of water containing rotting plants or animals, and mouldy hay or silage, where they produce a powerful toxin.
In winter, animals do not always get enough green forage. If they lack phosphorus, they chew anything from wire to stones, but especially bones. If they eat bones (or carcasses) containing the toxin, they may become infected with botulism.
Very severe botulism
Relatively rare, this occurs when large quantities of the poison are ingested. Signs appear within 24 hours. The animal’s muscles become weak, and it lies down, unable to move, its tongue protruding.
The signs are the same as when the disease is very severe, but take longer to develop, from two days to a week. Early on, an affected animal walks stiffly and slowly. It may still eat, but it will grow thin. The eyes become sunken and the coat gets rough.
The animal lives longer than eight days. It seldom lies down, but its legs become weak. It chews and swallows with difficulty. Some animals do not die, but become emaciated.
The first step in preventing botulism is to vaccinate animals. With cattle, do so when the calves are about six months of age and repeat four to seven weeks later, then every year thereafter. Even after vaccination, an animal may still get botulism, therefore:
- Burn or bury all carcasses, bones or rotting material. Remove dead chickens from the chicken house, as they can get trampled and buried in the straw used as bedding, where botulism can be produced. If cattle eat the straw, they may become infected.
- Giving livestock a supplement containing phosphate and calcium in dry months will prevent them from eating old bones and contaminated matter.
For more on vaccinations, contact your veterinarian or extension officer.
Source: Directorate Communication Services, department of agriculture.